The present invention relates to an installation (or an appliance or device) capable of operating at high temperature, in particular at temperatures of up to 550° C. and in particular of between 50 and 350° C., such as a cooking oven, in particular an oven intended for domestic use, and also to a thermal insulation product suited to the insulation of the said installation or the said oven, in particular suited to the insulation of heating boxes of the said ovens.
It is known to insulate oven parts, for example the heating (or cooking) enclosure (or chamber or box or muffle), in order to protect, from the heat or from overheating, the components (in particular electronic components) present around the enclosure or the external parts of the oven or, if appropriate, the item of furniture incorporating the oven, this insulation also making it possible to avoid heat losses to the outside of the enclosure and to improve the energy performance qualities of the oven during its use. The insulators used have to be in a position to withstand the high temperatures with which they are (at least temporarily) confronted and to retain their performance qualities (in particular mechanical or sufficient insulating performance qualities) at these temperatures without risk of deterioration or of emissions potentially dangerous to the health.
Ovens are generally insulated with fibrous insulators based on synthetic fibres, such as glass wall or rock wool, in particular by using felts or mats of mineral wool, which are installed or inserted, generally manually, around the enclosure. As the thickness and the density of the layers of mineral wools used is, however, limited by the capacities of the existing manufacturing lines, this can result in poorly insulated zones (thickness inappropriate for filling the changing spaces or reliefs of the oven housings) and thermal bridges, it being possible for this reason for the energy consumption of these normal ovens to remain relatively high.
In order to reduce the disadvantages related to the direct handling of mineral wool (irritation of the skin, dusts), the document WO 93/01444 furthermore provides for the insulation of objects such as ovens to be carried out by spraying a fibrous mineral material with simultaneous wetting of the fibres by water and/or a binder, followed by the shaping of the sprayed layer and then by the drying/hardening of the shaped layer. However, this technique presents problems of cleaning the work place, the various treatments carried out being in addition more expensive in time than that necessary for the positioning of conventional insulators, and it is difficult to control the amount of material deposited and to obtain a homogeneous density. The document WO 2001/036859 also provides an improved process in which the insulation is this time formed by insufflation of flocks of mineral wool between the surface to be insulated and a casing, such as a metal sheet or a surfacing mat, the flocks being conveyed by a gas stream while at least one jet of aqueous binder is directed onto them (making it possible to prevent flyaway of dusts, to convey and to apply the flocks and to subsequently stiffen the layer, once dry) in order to form a layer delimited by the casing, before drying in order to remove the water. However, this process remains lengthy, presents problems of coalescence of the adhesively bonded flocks which can result in a non-homogeneity in density at certain points, the density of flocks obtained in addition generally not exceeding 60 kg/m3, thus limiting the insulation performance qualities obtained.
The majority of the other insulators existing in other applications are for their part generally not suited to the insulation of installations subjected to high temperatures, these materials exhibiting, if appropriate, better thermal performance qualities at ambient temperature but being able to deteriorate or lose their good heat performance qualities at high temperature or over time. This is the case, for example, with cellular organic insulators of expanded polymer or foam type, these materials degrading in particular at high temperature. In the same way, vacuum insulators, as well as aerogels, are not conventionally used in ovens, these insulators, due to their nature and/or composition and/or components, exhibiting potential risks of degradation or of loss of their thermal performance qualities at high temperature and/or exhibiting a stiffness which does not allow them to conform to the contours of the oven. In addition, the binders, in particular organic binders, generally used in insulators in order in particular to provide them with mechanical integrity can, if appropriate, bring about undesirable gaseous emissions during the first operating cycles of the oven or at high temperature, for example during pyrolysis cycles.